98 research outputs found
Measuring the 8621 \r{A} Diffuse Interstellar Band in Gaia DR3 RVS Spectra: Obtaining a Clean Catalog by Marginalizing over Stellar Types
Diffuse interstellar bands (DIBs) are broad absorption features associated
with interstellar dust and can serve as chemical and kinematic tracers.
Conventional measurements of DIBs in stellar spectra are complicated by
residuals between observations and best-fit stellar models. To overcome this,
we simultaneously model the spectrum as a combination of stellar, dust, and
residual components, with full posteriors on the joint distribution of the
components. This decomposition is obtained by modeling each component as a draw
from a high-dimensional Gaussian distribution in the data-space (the observed
spectrum) -- a method we call "Marginalized Analytic Data-space Gaussian
Inference for Component Separation" (MADGICS). We use a data-driven prior for
the stellar component, which avoids missing stellar features not well-modeled
by synthetic spectra. This technique provides statistically rigorous
uncertainties and detection thresholds, which are required to work in the low
signal-to-noise regime that is commonplace for dusty lines of sight. We
reprocess all public Gaia DR3 RVS spectra and present an improved 8621 \r{A}
DIB catalog, free of detectable stellar line contamination. We constrain the
rest-frame wavelength to \r{A} (vacuum), find no
significant evidence for DIBs in the Local Bubble from the of
RVS spectra that are public, and show unprecedented correlation with kinematic
substructure in Galactic CO maps. We validate the catalog, its reported
uncertainties, and biases using synthetic injection tests. We believe MADGICS
provides a viable path forward for large-scale spectral line measurements in
the presence of complex spectral contamination.Comment: 25 pages, 25 figures, submitted to Ap
A Parsec-Scale Galactic 3D Dust Map out to 1.25 kpc from the Sun
High-resolution 3D maps of interstellar dust are critical for probing the
underlying physics shaping the structure of the interstellar medium, and for
foreground correction of astrophysical observations affected by dust. We aim to
construct a new 3D map of the spatial distribution of interstellar dust
extinction out to a distance of 1.25 kpc from the Sun. We leverage distance and
extinction estimates to 54 million nearby stars derived from the Gaia BP/RP
spectra. Using the stellar distance and extinction information, we infer the
spatial distribution of dust extinction. We model the logarithmic dust
extinction with a Gaussian Process in a spherical coordinate system via
Iterative Charted Refinement and a correlation kernel inferred in previous
work. We probe our 661 million dimensional posterior distribution using the
variational inference method MGVI. Our 3D dust map achieves an angular
resolution of 14' (Nside = 256). We sample the dust extinction in 516 distance
bins spanning 69 pc to 1250 pc. We obtain a maximum distance resolution of 0.4
pc at 69 pc and a minimum distance resolution of 7 pc at 1.25 kpc. Our map
resolves the internal structure of hundreds of molecular clouds in the solar
neighborhood and will be broadly useful for studies of star formation, Galactic
structure, and young stellar populations. It is available for download in a
variety of coordinate systems at https://doi.org/10.5281/zenodo.8187943 and can
also be queried via the publicly available dustmaps Python package
The Eighteenth Data Release of the Sloan Digital Sky Surveys: Targeting and First Spectra from SDSS-V
The eighteenth data release of the Sloan Digital Sky Surveys (SDSS) is the
first one for SDSS-V, the fifth generation of the survey. SDSS-V comprises
three primary scientific programs, or "Mappers": Milky Way Mapper (MWM), Black
Hole Mapper (BHM), and Local Volume Mapper (LVM). This data release contains
extensive targeting information for the two multi-object spectroscopy programs
(MWM and BHM), including input catalogs and selection functions for their
numerous scientific objectives. We describe the production of the targeting
databases and their calibration- and scientifically-focused components. DR18
also includes ~25,000 new SDSS spectra and supplemental information for X-ray
sources identified by eROSITA in its eFEDS field. We present updates to some of
the SDSS software pipelines and preview changes anticipated for DR19. We also
describe three value-added catalogs (VACs) based on SDSS-IV data that have been
published since DR17, and one VAC based on the SDSS-V data in the eFEDS field.Comment: Accepted to ApJ
The eighteenth data release of the Sloan Digital Sky Surveys : targeting and first spectra from SDSS-V
The eighteenth data release of the Sloan Digital Sky Surveys (SDSS) is the first one for SDSS-V, the fifth generation of the survey. SDSS-V comprises three primary scientific programs, or "Mappers": Milky Way Mapper (MWM), Black Hole Mapper (BHM), and Local Volume Mapper (LVM). This data release contains extensive targeting information for the two multi-object spectroscopy programs (MWM and BHM), including input catalogs and selection functions for their numerous scientific objectives. We describe the production of the targeting databases and their calibration- and scientifically-focused components. DR18 also includes ~25,000 new SDSS spectra and supplemental information for X-ray sources identified by eROSITA in its eFEDS field. We present updates to some of the SDSS software pipelines and preview changes anticipated for DR19. We also describe three value-added catalogs (VACs) based on SDSS-IV data that have been published since DR17, and one VAC based on the SDSS-V data in the eFEDS field.Publisher PDFPeer reviewe
Laser Application in Dentistry: Irradiation Effects of Nd:YAG 1064 nm and Diode 810 nm and 980 nm in Infected Root Canals - A Literature Overview
Objective. In endodontics, Nd:YAG laser (1064 nm) and diode laser (810 nm and 980 nm) devices are used to remove bacteria in infected teeth. A literature review was elaborated to compare and evaluate the advantages and disadvantages of using these lasers. Methods. Using combined search terms, eligible articles were retrieved from PubMed and printed journals. The initial search yielded 40 titles and 27 articles were assigned to full-text analysis. The studies were classified based upon laser source, laser energy level, duration/similarity of application, and initial and final bacterial count at a minimum of 20 prepared root canals. Part of the analysis was only reduced microorganisms and mechanically treated root canals upon preparation size of ISO 30. All studies were compared to evaluate the most favorable laser device for best results in endodontic therapy. Results. A total of 22 eligible studies were found regarding Nd:YAG laser 1064 nm. Four studies fulfilled all demanded criteria. Seven studies referring to the diode laser 980 nm were examined, although only one fulfilled all criteria. Eleven studies were found regarding the diode laser 810 nm, although only one study fulfilled all necessary criteria.Conclusions. Laser therapy is effective in endodontics, although a comparison of efficiency between the laser devices is not possible at present due to different study designs, materials, and equipment
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